ES2952783T3 - Hybrid water-based polyurethane/acrylate dispersions - Google Patents

Abstract

Embodiments described herein provide a coating composition that includes an aqueous acrylic/polyurethane dispersion. The aqueous acrylic/polyurethane dispersion is prepared from at least one isocyanate component, a mixture of polyols and at least one acrylate solvent. The polyol blend includes a polyester polyol and at least two different oleo-based polyols. The coating composition exhibits improved chemical resistance without sacrificing other properties, such as hardness and abrasion resistance. (Automatic translation with Google Translate, without legal value)

Description

description

Hybrid water-based polyurethane/acrylate dispersions

Cross reference to related requests

Technical field

Embodiments of the present disclosure relate generally to water-based polyurethane/acrylate hybrid dispersions and methods of manufacturing such coatings, and relate specifically to one-component water-based acrylic polyurethane coatings having improved chemical resistance.

Background

Water-based one-component polyurethane coatings are used in various applications. For example, these coatings can be used as binders for decorative, protective and industrial coatings, including wood coatings (floor or furniture coatings and others), kitchen cabinet coatings, PVC window frame coatings, PVC floor coatings , interior or exterior architectural coatings and primers, concrete floor coatings, automotive coatings and automotive plastic coatings, direct-to-metal coatings, industrial maintenance coatings, traffic marking paints, plastic coatings (i.e. for “3C” applications: computers, communications and consumer electronics), fireproof coatings, textile coatings, overprint varnishes, elastomeric roof coatings. The coatings can also be used in fiberglass sizing, as lamination adhesives for flexible packaging, gloss film lamination, furniture and automotive applications, shoe soles, electronics, heat seals, floor coverings, cementitious sealing slurries, putties for subfloors and walls, and as pressure sensitive adhesives. Additionally, the coatings may be suitable as binders for the production of putties and sealants, carpet backings, leather finishes, in the production of dipped articles (e.g. gloves), or as an emulsion vehicle for printing inks. Although one-component aqueous polyurethane coatings may be more environmentally friendly than solvent coatings and easier to use than two-component polyurethane compositions, their performance, and specifically, their chemical resistance, may not be as desirable as solvent-based or 2K alternatives.

US-8 637609 B1 describes a water-based 1K coating composition comprising aqueous acrylic/polyurethane dispersions.

US-2011/009561 A1 describes a water-based acrylic/polyurethane dispersion for coating applications.

US-2014/323638 A1 describes a process for preparing an acrylic/polyurethane hybrid dispersion derived from a natural oil polyol.

US-2012/041131 A1 describes radiation-curable coating compositions based on aqueous tin-free PU dispersions containing acrylate groups.

Consequently, there is a need for one-component water-based polyurethane coating compositions that reduce the use of solvent additives that cause increased levels of volatile organic compounds (VOCs) in the resulting coatings, while still providing superior properties. desirable coating characteristics, such as abrasion and chemical resistance. Additionally, higher chemical resistance binders designed for one-component water-based polyurethane coatings can also be used in two-component (2K) coatings, further improving their properties.

Summary

According to one embodiment, a coating composition is provided that includes an aqueous acrylic/polyurethane dispersion. The aqueous acrylic/polyurethane dispersion is produced from at least one isocyanate component, a mixture of polyols and at least one acrylate solvent. The polyol blend includes a polyester polyol, a polycarbonate polyol or a polyether polyol and at least two different oil-based polyols, wherein one of the at least two oil-based polyols comprises a hydroxyl-functionalized oil and wherein One of the at least two oil-based polyols comprises an oligomer derived from fatty acids. The coating composition exhibits improved chemical resistance without sacrificing other properties such as hardness and abrasion resistance.

According to another embodiment, a coated substrate is provided that includes a substrate and an acrylic/polyurethane coating disposed on the substrate. The acrylic/polyurethane coating is produced with the composition coating according to the invention. The polyol blend includes a polyester polyol and at least two different oil-based polyols.

In another embodiment, a method of manufacturing a one-component acrylic polyurethane coating composition includes preparing a polyol blend that includes a polyester polyol, a first oil-based polyol, and a different oil-based polyol. The method further includes mixing the polyol mixture with an isocyanate component in a reactive solvent including acrylic monomer.

Also disclosed is a method (not according to the invention) for producing a two-component acrylic polyurethane coating composition that includes mixing the component containing the acrylic polyurethane binder and a suitable hardener.

Detailed description

Embodiments relate to acrylic polyurethane coatings produced from the reaction of isocyanates and polyol mixtures including at least two oil-based polyols in the presence of a reactive acrylate solvent. The resulting acrylic polyurethane coatings manufactured using the polyol blend including a polyester polyol and at least two oil-based polyols in the presence of a reactive acrylate solvent reduce the need for typical solvent additives that cause increased compound loading. volatile organic compounds (VOCs) in the coating, while still achieving desirable coating properties such as hardness, abrasion resistance and chemical resistance.

In some embodiments, the acrylic polyurethane coating is in dispersion form. As used herein, the term “dispersion” refers to polymeric solids distributed in an aqueous medium. In certain embodiments, the acrylic polyurethane coating is in the form of a hybrid acrylic/polyurethane dispersion wherein the acrylate-grafted polyurethane solids are dispersed in water. Acrylate-grafted polyurethane solids, more specifically, include one or more acrylate polymer chains obtained from one or more acrylate monomers grafted onto a polyurethane polymer backbone. In various embodiments, the acrylic polyurethane hybrid dispersion includes between 20% and 50% by weight solids. In some embodiments, the acrylic polyurethane dispersion includes between 30% and 40% by weight solids.

In various embodiments, the acrylic/polyurethane hybrid dispersion is used in a formulation for a one-component acrylic polyurethane coating. Generally, the formulation includes an isocyanate component, a polyol blend, at least one acrylate solvent, and, optionally, at least one acrylate/urethane cross-linker. The isocyanate component may be, in various embodiments, an aliphatic diisocyanate or a polyisocyanate. According to various embodiments, the polyol blend generally includes at least two oil-based polyols. In some embodiments, the polyol blend may further include a polyester polyol.

In various embodiments, the acrylic polyurethane coating composition may include from about 2% by weight to about 25% by weight, from about 5% by weight to about 20% by weight, or from about 10% by weight at approximately 15% by weight of the polyol mixture with respect to the weight of the aqueous acrylic polyurethane dispersion.

In some embodiments, the polyol blend may include at least one polyester polyol. The polyester polyol may have a number average molecular mass of about 400 to about 6,000 g/mol, or even about 600 to about 2,500 g/mol, and an OH functionality of about 1.8 to about 4, or even about 2 to about 3. In some embodiments, the polyol polyester is obtained by polycondensation of dicarboxylic acids with polyols. Dicarboxylic acids can be aliphatic, cycloaliphatic or aromatic, and/or their derivatives, such as anhydrides, esters or acid chlorides. Some examples may be succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid or sebacic acid, phthalic acid, isophthalic acid, trimellitic acid, phthalic anhydride, anhydride rhophthalic tet rahid, glutaric anhydride, maleic acid, maleic anhydride, fumaric acid, dimeric fatty acid and dimethyl terephthalate. Suitable polyols include, but are not limited to, monoethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 3-methylpentane-1,5-diol, neopentylglycol (2,2-dimethyl- 1,3-propanediol), 1,6-hexanediol, 1,8-octanoglycol, cyclohexanedimethanol, 2-methylpropane-1,3-diol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, dipropylene glycol, polypropylene glycol, dibutylene glycol and polybutylene glycol. In some embodiments, the polyester polyol may be a polycaprolactone polyol or a hyperbranched polyol. In a particular embodiment, the polyester polyol is a polyester diol of hexanediol and adipic acid with an average molecular mass of about 1,000 g/mol and an OH functionality of 2. A suitable polyester polyol is commercially available as Hoopol F-920 from Synthesia Internacional SLU (Barcelona, Spain).

In some embodiments, the polyester polyol may be replaced by other types of polyols, including polycarbonate polyols and polyether polyols.

Suitable polycarbonates are those obtained, for example, by reaction of carbonic acid derivatives, for example diphenyl carbonate, dimethyl carbonate or phosgene, with polyols, preferably diols. Useful diols of this type include, for example, ethylene glycol, propane-1,2- and 1,3-diol, butane-1,3- and 1,4-diol, hexane-1,6-diol, octane-1 ,8-diol, neopentyl glycol, 1,4-bishydroxymethylcyclohexane, 2-methylpropane-1,3-diol, 2,2,4-trimethylpentane-1,3-diol, dipropylene glycol, polypropylene glycols, dibutylene glycol, polybutylene glycols, bisphenol A, tetrabromobisphenol A , but also lactone-modified diols.

Suitable polyether polyols are preferably the polyaddition products of styrene oxides, ethylene oxide, propylene oxide, tetrahydrofuran, butylene oxide, epichlorohydrin, and mixed addition and grafting products thereof, and polyether polyols obtained by condensation of polyhydric alcohols or mixtures thereof and those obtained by alkoxylation of polyhydric alcohols, amines and amino alcohols.

In some embodiments, the polyol blend may include from about 1% by weight to about 90% by weight of the polyester polyol, or from about 10% by weight to about 90% by weight of the polyester polyol, or from about 30% by weight to about 80% by weight of the polyester polyol or from about 50% by weight to about 70% by weight of the polyester polyol with respect to the weight of the polyol mixture in the dispersion. When polycarbonate or polyether polyols are used in place of the polyester polyol, they may be included in the same amounts as the polyester polyols described herein.

The polyol mixture may further include at least two different oil-based polyols. As used herein, the term “oil-based polyol” refers to a polyol derived from vegetable and/or animal fats. For example, in some embodiments, the polyol blend includes a hydroxyl-functionalized oily polyol and an oligomeric alcohol derived from fatty acids.

The hydroxyl-functionalized oil polyol may be, in some embodiments, a vegetable oil that has been epoxidized and subjected to nucleophilic attack. The vegetable oil may be, but is not limited to, castor oil, linseed oil or soybean oil. Other oils can be used, among others, sunflower oil, rapeseed oil or similar. In such embodiments, the nucleophilic reagent may be, but is not limited to, water, an alcohol, an alkanolamine or an amine. The resulting functionalized oil may optionally undergo ethoxylation or propoxylation. In a particular embodiment, the hydroxyl-functionalized oil polyol is an ethoxylated vegetable oil with an OH value of 80 mg KOH/g and an average functionality of about 3.1. A suitable hydroxyl-functionalized oil polyol is commercially available as Merginol® 207 from Hobum Oleochemicals GmbH (Hamburg, Germany).

In various embodiments, the hydroxyl functionalized oil polyol may have the following structure:

where A, A' and A” are independently selected from:

and

wherein X is independently selected from -OH, -OROH, -NHROH, -N(ROH) ₂ or -OC(O)R; R is independently selected from any alkyl chain, -(CH ₂ -CH ₂ -O) ⁿ CH ₂ CH ₂ - or -(CH ₂ -CH(CH ₃ )-O) ⁿ CH ₂ -CH(CH ₃ )-; and y', y” , y'“ , z', z” , and z'“ are independently selected to be an integer from 1 to 16.

It is also contemplated that the chemical modification of the natural oil is incomplete, and that some unreacted molecules may be present (for example, unsaturations or other intermediate molecules). In addition, groups X and R different from those indicated above are contemplated. In some particular embodiments, the hydroxyl functionalized oil polyol may have the following structure:

where each of

The polyol mixture may include from about 1 wt % to about 70 wt % of the hydroxyl functionalized oil polyol, or from about 5 wt % to about 50 wt % of the hydroxyl functionalized oil polyol or from about 15% by weight to about 30% by weight of the hydroxyl-functionalized oil polyol with respect to the weight of the polyol mixture in the dispersion.

In various embodiments, the polyol mixture may further include at least one oligomeric alcohol derived from fatty acids. The oligomeric alcohol derived from fatty acids may be, but is not limited to, a dimer, a trimer or a tetramer derived from one or more fatty acids. The fatty acids from which the oligomer is derived may be short chain fatty acids, medium chain fatty acids or long chain fatty acids, or a combination thereof. In some embodiments, the fatty acid from which the oligomer is derived is a medium chain fatty acid, a long chain fatty acid, or a combination thereof. As used herein, a “medium chain fatty acid” refers to a fatty acid having between 6 and 12 carbon atoms. As used herein, a “long chain fatty acid” refers to a fatty acid having more than 12 carbon atoms. In some embodiments, the fatty acid may be a dimerized fatty acid. In some embodiments, the oligomer is a diol dimer or triol trimer derived from one or more medium or long chain fatty acids.

In a particular embodiment, the oligomeric alcohol derived from fatty acids is a diol dimer obtained by the conversion of unsaturated fatty acids into a molecule with 36 carbon atoms by dimerization and reduction of the resulting diacid to a diol. The resulting diol dimer may have an OH value of about 202 to about 212 mg KOH/g. A suitable diol dimer is commercially available as Pripol™ 2033 from Croda International Plc (Snaith, England).

In some embodiments, the polyol mixture may include from about 1% by weight to about 70% by weight of the oligomer derived from fatty acids, or from about 5% by weight to about 50% by weight of the oligomer derived from fatty acids or from about 10% by weight to about 25% by weight of the oligomer derived from fatty acids with respect to the weight of the mixture of polyols in the dispersion.

Various compositions are considered suitable for the isocyanate component. The isocyanate component includes one or more aliphatic or aromatic isocyanates, condensation products thereof or derivatives thereof. In some embodiments, the isocyanate has a functionality of about 1 to about 3. The isocyanate may be, for example, an aliphatic or aromatic diisocyanate, a condensation product of an aliphatic or aromatic diisocyanate, or a derivative of an aliphatic or aromatic diisocyanate. such as an allophonate, biruret, isocyanurate, urethane, iminooxadiazindione, oxadiazintrione or uretdione. In various embodiments, the isocyanate component includes at least one aliphatic diisocyanate.

For example, in some embodiments the isocyanate component may include tetramethylene diisocyanate, hexamethylene diisocyanate, 2,2,4- and/or 2,4,4-trimethylhexamethylene diisocyanate, pentamethylene diisocyanate (PDI), 1,8- isocyanato-methyloctane diisocyanate, cyclohexylene 1,4-diisocyanate, phenylene 1,4-diisocyanate, 1,3-and 1,4-bis(2-isocyanato-prop-2-yl)benzene (TMXDI), 1, 3-bis(isocyanomethyl)benzene (XDI), naphthalene 1,5-diisocyanate, triphenylmethane 4,4',4”-triisocyanate, 4,4'-diisocanato-diphenylmethane, 2,4'-diisocyanato-diphenylmethane, 2 ,4-diisocyanatotoluene, 2,6-diisocyanato-toluene, a,a,a',a'-tetramethyl-m- or -p-xylylene diisocyanate, 4,4'-, 2,2'- and 2,4' -diisocyanato-dicyclohexylmethane (H12MDI) or mixtures thereof with any isomer content, 1-isoscyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane (isophorone diisocyanate), a condensation product thereof, a derivative thereof such as an allophonate, biruet, isocyanurate, urethane, iminooxadiazindione, oxadiazintrione or uretdione, and mixtures thereof. In a particular embodiment, the isocyanate component is 4,4'-diisocyanato-dicyclo-hexylmethane (H12MDI).

The amount of isocyanate component may vary depending on the application. In some embodiments, the polyurethane coating composition may include from about 4 weight % to about 20 weight %, from about 6 weight % to about 15 weight % or even from about 8 weight % to approximately 12% by weight of the isocyanate with respect to the weight of the aqueous dispersion of acrylic polyurethane.

In various embodiments, the isocyanate component and the polyol mixture are mixed in a reactive solvent that includes one or more acrylic components, such as one or more acrylic monomers. In some embodiments, the one or more acrylic monomers may be, for example, one or more acrylic acid ester monomers, one or more methacrylic acid ester monomers, or a combination thereof. Suitable monomers include, but are not limited to, acrylic acid, methacrylic acid, methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, butyl, 2-ethylhexyl methacrylate, styrene, methylstyrene, isobornyl acrylate and the like. In a particular embodiment, the reactive acrylic solvent is methyl methacrylate (MMA). Without being limited by theory, it is believed that the reactive acrylic solvent can reduce or eliminate the need for a VOC solvent, reduce the cost of coating formulation and provide synergistic properties, as the grafted acrylate is homogeneously distributed in the matrix of polyurethane.

In various embodiments, the coating formulation further includes one or more acrylate/urethane cross-linkers that can be used as an acrylic capping agent to allow the formation of acrylic-polyurethane graft copolymers, improving compatibility between the acrylic and polyurethane components. The acrylate/urethane cross-linker may be, for example, a hydroxyl functional linker containing double bonds. The double bond containing hydroxyl functional linker contains double bonds that can be polymerized by free radical polymerization, such as hydroxy functional acrylates and/or methacrylates. Some examples of suitable acrylate/urethane crosslinkers are, among others, 2-hydroxyethyl(meth)acrylate (HEMA), polyethylene oxide mono(meth)acrylates, polypropylene oxide mono(meth)acrylates, polypropylene oxide mono(meth)acrylates, polyalkylene oxide (meth)acrylates, poly(s-caprolactone) mono(meth)acrylates, 2-hydroxypropyl(meth)acrylate, 4-hydroxybutyl(meth)acrylate, 3-hydroxy-2,2-dimethylpropyl (me)acrylate, mono-, di-, tri- or tetraacrylates of polyhydric alcohols, such as trimethylolpropane, glycerol, pentaerythritol, dipentaerythritol, ethoxylated, propoxylated or alkoxylated trimethylolpropane, glycerol, pentaerythritol, dipentaerythritol or technical grade mixtures thereof. In some embodiments, the acrylate/urethane crosslinkers may include alcohols that can be obtained from the reaction of acids containing double bonds with monomeric epoxide compounds that optionally contain double bonds, such as the reaction products of (meth)acrylic acid with glycidyl (meth)acrylate or with the glycidyl ester of versatic acid. In a particular embodiment, the acrylate/urethane cross-linker is 2-hydroxyethyl(meth)acrylate (HEMA). The amount of acrylate/urethane crosslinkers may be about 0.05 wt.% to about 2 wt.%, about 0.1 wt.% to about 1 wt.%, or about 0.2 % by weight to approximately 0.5% by weight of the aqueous acrylic polyurethane dispersion.

The formulation may also include additives or other modifiers. For example, one or more polymerization catalysts may be used. Catalysts may include, but are not limited to, amine catalysts, tin catalysts, peroxide catalysts and the like. In some embodiments, amine and/or organometallic catalysts (e.g., tin, bismuth, zirconium, zinc) may be used for the polycondensation reaction that produces the polyurethane, while a peroxide catalyst may be used for the polymerization of acrylic. In some embodiments, the polyurethane coating composition may be free of amine and/or tin catalysts. The total amount of catalyst can be about 0.01% by weight to about 0.2% by weight, from about 0.03% by weight to about 0.15% by weight or from about 0.05% by weight to about 0.1% by weight of the polyurethane coating composition, depending on the nature of the isocyanate and acrylic monomers and/or depending on whether the catalyst is provided in a carrier, as would be understood by a person of ordinary skill in the art. Tin catalysts may include tin salts, such as stannous salts of carboxylic acids. Amine catalysts may include, but are not limited to, tertiary amine catalysts. Tertiary amine catalysts include organic compounds that contain at least one tertiary nitrogen atom and are capable of catalyzing the hydroxyl/isocyanate reaction between the isocyanate component and the isocyanate reaction mixture. Peroxide catalysts can be any of various inorganic peroxide compounds or organic hydroperoxide compounds known to be active in the production of free radicals to initiate polymerization, provided that said compounds are soluble in the aqueous/organic media in which it takes place. polymerization. Peroxide catalysts include ammonium and alkali metal persulfates, tertiary alkyl hydroperoxides, such as tertiary butyl hydroperoxide, and the like.

The formulations may also include other additives, such as additives known to one skilled in the art for use in acrylic polyurethane coatings. Some examples of additives are fillers, chain extenders, moisture scavengers, release agents, antifoam agents, adhesion promoters, cures, pH neutralizers, UV stabilizers, antioxidants, plasticizers, compatibilizers, flame retardants, flame suppressing agents, smoke suppressing agents, antimicrobial agents, air release agents, rheology modifiers, wetting additives and/or pigments/dyes. For example, pigments such as titanium dioxide and/or carbon black may be used to impart color properties to the acrylic polyurethane coating composition. The pigments may be in the form of solids or the solids may be predispersed in a resin carrier before being added to the acrylic polyurethane coating composition.

The acrylic polyurethane coating composition may further include one or more stabilizing anionic polyols, which stabilize the dispersion. The stabilizing anionic polyol may be present in an amount of about 0.2% by weight to about 7% by weight, from about 0.5% by weight to about 5% by weight or about 1.0 % by weight to approximately 3% by weight of the aqueous acrylic polyurethane dispersion. The stabilizing anionic polyol may be, but is not limited to, dimethylolpropionic acid (DMPA), dimethylolacetic acid, dimethylolbutanoic acid (DMBA), dimethylolvaleric acid/sulfonate, hydroxypivalic acid, dihydroxysuccinic acid, or combinations thereof. It is also possible to use sulfonic acid diols optionally having ether groups, of the type described in US Patent 4,108,814. In a particular embodiment, the stabilizing anionic polyol is dimethylolpropionic acid (DMPA).

In various embodiments, the acrylic polyurethane coating composition does not contain cosolvents. As used herein, the term "cosolvent" refers to the solvents used in addition to the reactive acrylate solvent and the polyols present in the polyol mixture. Such cosolvents may include, but are not limited to, glycols, glycol ether, 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate, alcohols, mineral spirits, and benzoate esters.

In various embodiments, the acrylic polyurethane coating composition is prepared as a one-component system, i.e., an aqueous dispersion. In such embodiments, a polyurethane prepolymer is formed by mixing the reaction components, which includes the polyol mixture, the reactive acrylate solvent, the catalyst and with an excess amount of the isocyanate component. For example, the reaction components can be added to a reactor and the reaction can be allowed until a constant isocyanate content is obtained. In various embodiments, the reaction is allowed to proceed until the amount of unreacted isocyanate groups (%NCO) is between about 3% and about 4%. In a particular embodiment, the %NCO is approximately 3.4%. In some embodiments, a portion of the acrylate monomer (in the reactive acrylate solvent) may be added to the polyurethane once created. However, in some embodiments, at least a portion of the reactive acrylate solvent is added prior to dispersion in water to reduce viscosity and assist dispersion.

Before dispersion in water, the stabilizing anionic polyols are neutralized with a suitable neutralizing agent. The neutralizing agent can also be added to the water in which the prepolymer is to be dispersed before the dispersion process takes place. Suitable neutralizing agents may be selected, for example, from the group consisting of triethylamine, N-ethylmorpholine, dimethylisopropylamine, ethyldiisopropylamine, dimethylcyclohexylamine, triethanolamine, dimethylethanolamine, ammonia, potassium hydroxide, sodium hydroxide and any desired mixture thereof. After dispersing the prepolymer in water, a suitable chain extender is added to the resulting dispersion which reacts with the remaining isocyanate groups and increases the molecular mass of the polymer. The reactive NCO groups used in the chain extender generally contain amino groups, since both primary and secondary amines are very reactive towards NCO groups, but they may also contain hydroxyl groups. The water present in the dispersion as a continuous phase can also be used as a chain extender in the absence of other more reactive chain extenders. Suitable chain extenders include, for example, ethylene-1,2-diamine, 1,2- and 1,3-diaminopropane, 1,4-diaminobutane, 1,6diaminohexane, isophoronediamine, a mixture of isomers of 2,2,4- and 2,4,4-trimethylhexamethylenediamine, 2-methylpentamethylenediamine, diethylenetriamine, 4,4-diaminodicyclohexylmethane, hydrazine hydrate and/or dimethylethylenediamine, diethanolamine, 3- amino-1-methylaminopropane, 3-amino-1-ethylaminopropane, 3-amino-1-cyclohexylaminopropane, 3-amino-1-methylaminobutane, alkanolamines such as N-aminoethylethanolamine, ethanolamine, 3-aminopropanol, neopentanolamine, adipic dihydrazide, oxalic dihydrazide, carbohydrazide, succinic dihydrazide, or longer chain aminofunctional compounds such as polyetheramines (“Jeffamines”). Once the polymer chain extension has been carried out, a catalyst and a reducing agent can be added to polymerize the prepolymer. Following polymerization, the acrylic polyurethane coating composition may be sprayed or otherwise deposited onto a substrate. The substrate may be, but is not limited to, a wooden substrate, such as a wooden floor or furniture, or another suitable type of substrate, for example paper, glass, metal, plastics and the like. The acrylic polyurethane polymer is then dried and the polymer particles bond together to form a film on the substrate.

In various embodiments, the acrylic polyurethane coating has a pendulum hardness greater than about 98 s, about 98 s to about 130 s, about 99 s to about 120 s, or about 99 s to about 102 s, when measured according to the ISO standard. 1522. In some embodiments, the acrylic polyurethane coating exhibits a Taber abrasion of less than about 60 mg or less than about 50 mg when measured on a CS 17 roller at 1,000 rpm and 1,000 g. Furthermore, the acrylic polyurethane coating is believed to exhibit chemical resistance to substances according to DIN 68661 1A. Specifically, various embodiments provide an acrylic polyurethane coating having an ethanol resistance greater than or equal to about 4, measured according to DIN 68661 1A and evaluated according to DIN EN 12720.

Examples

The following examples are provided to illustrate various embodiments. All parts and percentages are expressed by weight, unless otherwise indicated.

Listed in Table 1 are Example 1, which is an illustrative embodiment of the present formulation that includes a polyester polyol, two oil-based polyols and an acrylate solvent, and Comparative Examples 1-4, which include a polyester polyol. polyester, an acrylate solvent and only one oil-based polyol in proportions equal to their content in Example 1 or to the content of both oil-based polyols together in Example 1. In the examples, Hoopol F920 (a hexanediol adipate with an average molecular mass of 1,000 g/mol available from Synthesia Group) was added as a polyester polyol, Merginol® 207 (an ethoxylated oil-based polyol with an average functionality of 3.1 and an average OH value of 80 mg of KOH/g available from Hobum Oleochemicals GmBH), and Pripol™ 2033 (a diol dimer with an average OH value of 202-212 mg KOH/g available from Croda International Plc).

The compositions in Table 1 were prepared by combining the polyol mixture with 90 g of the reactive acrylic solvent, the stabilizer and the acrylate linker and mixing at 60 °C to achieve complete homogenization. H12MDI was added to the homogenized mixture for 10 minutes at a temperature between approximately 50 0C and approximately 60 0C.

The temperature of the mixture was raised to a temperature between 65 0C and 70 0C and, once the indicated %NCO was reached, an additional 90.00 g of MMA was added to each composition and mixed. After mixing until homogenous, approximately 20.40 g of triethylamine was added to each composition to neutralize the DMPA and render it anionic. Each composition was cooled and distilled water was added with stirring to obtain a homogeneous dispersion.

A diamine solution was added to each dispersion until the %NCO was less than approximately 0.20%. The resulting dispersions were then heated to 40 0C and a 6% aqueous solution of ammonium persulfate and a stoichiometric amount of Bruggolite FF6 as a 1.5% aqueous solution were added to initiate the polymerization. The reaction mixture was then heated to 80 0C and maintained at this temperature until the polymerization was completed. The resulting dispersions were then cooled to 45 0C and a reducing agent was added. Next, a 5% aqueous solution of fert-butyl hydroperoxide was added to initiate the polymerization of the residual monomer that had not reacted during the first polymerization reaction. Each reaction mixture was maintained at 45 0C during the second polymerization reaction.

The resulting dispersions were used as binders to formulate a transparent coating. In particular, Example 2 included the dispersion of Example 1, Comparative Example 5 included the dispersion of Comparative Example 1, Comparative Example 6 included the dispersion of Comparative Example 2, Comparative Example 7 included the dispersion of Comparative Example 3, and Comparative Example 8 included the dispersion of Comparative Example 4. Additionally, Comparative Example 9 was formulated using Ecrothan™ 2012, a hybrid acrylic polyester polyurethane that does not include an oil-based polyol available from Michelman, Inc. (Cincinnati, Ohio). Water, butyl glycol (a coalescent agent) and various additives were added to each binder. As indicated in Table 2, water was added in two parts, Part 1 was used to dilute the butyl glycol to 50%. In particular, the additives included TEGO® Twin 4200 (a wetting additive commercially available from Evonik Industries AG (Essen, Germany)), Acrysol™ RM-825 (a nonionic urethane rheology modifier commercially available from The Dow Chemical Company (Midland, MI)), and BYK-093 (a VOC-free silicone-containing defoamer commercially available from BYK USA Inc. (Wallingford, CT)). The coating compositions are indicated in Table 2 in grams (g).

The pendulum hardness was measured for each of the coating compositions according to ISO 1522 after 24 hours and after 7 days. Gloss retention was measured for each of the coating compositions according to ISO 2813 at 20°, 60° and 85°. The Taber abrasion of each of the coating compositions was measured with a CS 17 roller at 1,000 rpm and 1,000 g. The results of pendulum hardness, gloss and Taber abrasion test are provided in Table 3 below.

As shown in Table 3, the coating of Example 2 exhibited similar gloss retention properties as Comparative Example 9, where a one-component (1K) polyurethane/acrylic binder was employed without solvents (i.e., without organic solvents). Example 2 also showed extraordinarily rapid hardness development (i.e., 24 hour hardness). Comparative Examples 5 and 7, both containing only the hydroxyl-functionalized oil-based polyol, had hardness development and gloss retention properties similar to those of Example 2 at each measured angle. However, Comparative Examples 5 and 7 had unacceptably low abrasion resistance. Comparative Examples 6 and 8, which in both cases only contain the diol dimer, demonstrated pendulum hardness, gloss retention and Taber abrasion values similar to those of Example 2.

The coatings were also subjected to a series of chemical resistance tests according to DIN 68661 1A and evaluated according to DIN EN 12720. Each of the chemicals listed in Table 4 was subjected to stress for 16 hours at room temperature . The results of each of the tests are presented in Table 4 on a scale of 1 to 5, where 1 is the worst and 5 is the best.

As shown in Table 4, compositions including two oil-based polyols (Example 2) or different proportions of the hydroxyl-functionalized oil-based polyol (Comparative Examples 5 and 7) showed better chemical resistance to ethanol and acetone than the composition that did not include oil-based polyols (Comparative Example 9). Example 2 and Comparative Example 9 further showed similar chemical resistance to coffee, water, Atrix, Nivea Soft, red wine, the plasticizer Loxanol 5060 and ammonia. While Comparative Examples 6 and 8, which contain different proportions of the diol dimer, but do not contain the hydroxyl-functionalized oil-based polyol, had previously demonstrated pendulum hardness, gloss retention and Taber abrasion values similar to those of Example 2 demonstrated poor resistance to ethanol and acetone (8). Surprisingly, the combination of two oil-based polyols with a polyester polyol resulted in improved chemical resistance, while maintaining other coating properties, such as pendulum hardness, gloss retention and Taber abrasion. This versatility in chemical resistance allows the coating to protect against damage caused by a wide range of chemicals.

Claims (11)

re iv in d ic at io ns 1. A coating composition comprising an aqueous acrylic/polyurethane dispersion, wherein the aqueous acrylic/polyurethane dispersion is produced from: at least one isocyanate component; a mixture of polyols, the polyol mixture comprising a polyester polyol, a polycarbonate polyol or a polyether polyol and at least two different oil-based polyols, wherein one of the at least two oil-based polyols comprises a functionalized oil with hydroxyl and wherein one of the at least two oil-based polyols comprises an oligomer derived from fatty acids; and at least one acrylate solvent. 2. The coating composition of claim 1, wherein the fatty acid derived oligomer comprises a diol dimer or a triol trimer. 3. The coating composition of claim 2, wherein the diol dimer or triol trimer is derived from fatty acids selected from the group consisting of short chain fatty acids, medium chain fatty acids, long chain fatty acids. long and combinations thereof. 4. The coating composition of any preceding claim, wherein one of the at least two oil-based polyols comprises a hydroxyl-functionalized oily polyol and another of the at least two oil-based polyols comprises a diol dimer derived from fatty acids. . 5. The coating composition of any preceding claim, wherein the at least one isocyanate component is present in an amount of 4 to 20% by weight with respect to the weight of the aqueous acrylic/polyurethane dispersion. 6. The coating composition of any preceding claim, wherein the at least one isocyanate component comprises an aliphatic diisocyanate. 7. The coating composition of any preceding claim, wherein the at least one acrylate solvent comprises an acrylic or methacrylic monomer or mixtures thereof. 8. The coating composition of any preceding claim, further comprising at least one acrylate/urethane crosslinker. 9. A coated substrate, comprising: a substrate; and an acrylic/polyurethane coating disposed on the substrate, wherein the acrylic/polyurethane coating is produced from a coating composition according to any one of the preceding claims. 10. The coated substrate of claim 9, wherein at least one of the oil-based polyols comprises a hydroxyl-functionalized oily polyol and another of the oil-based polyols comprises a diol dimer derived from fatty acids. 11. A method of manufacturing a one-component aqueous polyurethane/acrylic coating composition, comprising: preparing a polyol blend comprising a polyester polyol, a polycarbonate polyol or a polyether polyol and at least two different oil-based polyols, wherein one of the at least two oil-based polyols comprises a hydroxyl-functionalized oil and wherein one of the at least two oil-based polyols comprises an oligomer derived from fatty acids; and mixing the polyol mixture with at least one isocyanate component in at least one acrylate solvent.